There are a variety of base configurations for biaxially stretched blow molded PET containers on the market. These include configurations, for example, described in U.S. Pat. Nos. 3,935,955 and 4,785,949. The former (see FIGS. 5 and 6) comprises a central concave dome portion and a plurality of triangular foot portions. However, stress cracks or even rupture is initiated in such base configuration when the applied pressure exceeds a certain critical level. The latter (see FIGS. 7 and 8) comprises a central convex portion and five radiating legs, and is characterized in that the legs and feet are generally of the same outline as the ribs and legs of a base configuration having six legs and feet, thereby rendering the ribs between the feet of greater width. Although this base configuration may increase the cross sectional area of the rib, it is inevitable to use a concave corner to connect the leg with the rib, thus easily resulting in cracking in the concave corner portions.
Therefore, it is an object of the present invention to provide a base configuration for biaxial stretched blow molded PET containers which may obviate and mitigate the above-mentioned drawbacks.